Objective  To analyze the cause of nucleus pulposus residue after percutaneous endoscopic lumbar discectomy(PELD).Methods  From August 2012 to July 2017，315 patients with primary lumbar disc herniation(LDH) were treated with PELD.There were 193 males and 122 females.The patients aged from 16 to 81 years，with an average age of 43.5 years.307 patients had single level procedure，7 patients had double level procedure，and 1 patients had three level procedure.102 patients were treated by intralaminar approach，and 213 patients were treated by transforaminal approach.Lumbar MRI or CT was checked after the operation.According to the result of MRI or CT，The patients were divided into residue group or non-residue group.All patients were followed up for 4 months to 5 years.The gender，age，operation approach，0swestry disability index(ODI)，and visual analogue scale(VAS) were analyzed between the two groups.Results  Nucleus pulposus residue happened in 26 patients and the incidence rate was 8.25%.There were 9 females and 17 males.All the patients had single level LDH，including 10 discs of L₅S₁ and 16 discs of L_4～5.7 patients were treated by intralaminar approach，and 19 patients were treated by transforaminal approach.Only 2 patients needed second procedure.There was no significant difference between the two groups in the gender，age，operation approach，ODI before operation，and VAS before operation.There was significant difference between the two groups in the ODI after operation，and VAS after operation.Conclusion  Nucleus pulposus residue is a common complication after PELD.Insufficent surgical experience is the primary cause.Part of the patients are unsatisfied with the result，but few of the patients need second operation.